bench: move module and imports in FizzyEngine::instantiate

[gumb0]

Clang 10 build with LTO

fizzy/instantiate/blake2b_mean                                     -0.0239         -0.0245            54            53            54            52
fizzy/instantiate/ecpairing_mean                                   -0.0485         -0.0403          2838          2701          2839          2724
fizzy/instantiate/keccak256_mean                                   -0.0375         -0.0315            94            90            94            91
fizzy/instantiate/memset_mean                                      -0.0617         -0.0592            18            17            18            17
fizzy/instantiate/mul256_opt0_mean                                 -0.0645         -0.0613            22            20            22            20
fizzy/instantiate/ramanujan_pi_mean                                -0.0103         -0.0079            57            56            57            56
fizzy/instantiate/sha1_mean                                        -0.0218         -0.0205            84            82            84            82
fizzy/instantiate/sha256_mean                                      -0.0218         -0.0209           137           134           137           134
fizzy/instantiate/taylor_pi_mean                                   -0.0674         -0.0671            12            11            12            11
fizzy/instantiate/micro/eli_interpreter_mean                       -0.0433         -0.0424            15            14            15            14
fizzy/instantiate/micro/factorial_mean                             -0.1114         -0.1120             3             2             3             2
fizzy/instantiate/micro/fibonacci_mean                             -0.1179         -0.1188             3             3             3             3
fizzy/instantiate/micro/host_adler32_mean                          -0.1361         -0.1366             8             7             8             7
fizzy/instantiate/micro/spinner_mean                               -0.1040         -0.1041             3             2             3             2
fizzy/instantiate/stress/guido-fuzzer-find-1_mean                  -0.0301         -0.0300           327           317           327           317

[codecov]

Codecov Report

Merging #581 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #581   +/-   ##
=======================================
  Coverage   98.23%   98.23%           
=======================================
  Files          62       62           
  Lines        8990     8990           
=======================================
  Hits         8831     8831           
  Misses        159      159           

[chfast]

fizzy/instantiate/blake2b_mean                                     -0.0423         -0.0423            28            27            28            27
fizzy/instantiate/ecpairing_mean                                   -0.0059         -0.0059          1394          1386          1394          1386
fizzy/instantiate/keccak256_mean                                   -0.0373         -0.0373            48            46            48            46
fizzy/instantiate/memset_mean                                      -0.0402         -0.0402            10             9            10             9
fizzy/instantiate/mul256_opt0_mean                                 -0.0184         -0.0184            12            12            12            12
fizzy/instantiate/ramanujan_pi_mean                                -0.0365         -0.0365            29            28            29            28
fizzy/instantiate/sha1_mean                                        -0.0408         -0.0408            43            41            43            41
fizzy/instantiate/sha256_mean                                      -0.0383         -0.0383            70            67            70            67
fizzy/instantiate/taylor_pi_mean                                   -0.0470         -0.0470             7             6             7             6
fizzy/instantiate/micro/eli_interpreter_mean                       -0.0304         -0.0304             8             8             8             8
fizzy/instantiate/micro/factorial_mean                             -0.1003         -0.1003             1             1             1             1
fizzy/instantiate/micro/fibonacci_mean                             -0.0847         -0.0847             2             1             2             1
fizzy/instantiate/micro/host_adler32_mean                          -0.0704         -0.0704             4             4             4             4
fizzy/instantiate/micro/spinner_mean                               -0.1113         -0.1113             1             1             1             1
fizzy/instantiate/stress/guido-fuzzer-find-1_mean                  -0.0372         -0.0372           153           147           153           147

[axic]

I think the commit log is wrong, this is not about bench. Also this should be mentioned in the changelog when the time comes.